In the cellulose industry, paper pulp is produced by cooking wood chips with cooking liquors. After the cooking, the requirement is to recover the chemicals and energy in the spent liquors by means of combustion. This takes place following evaporation in recovery boilers.
As a consequence of more stringent environmental restrictions, an ever greater amount of the material which was previously discharged from pulp mills is now recirculated. This results in increased contents of non-process elements such as chloride and potassium.
In addition to this, it is becoming ever more important to keep the contents of chloride and potassium in the chemical cycle at a low level in order to ensure trouble-free operation in association with high steam values.
For these reasons, there is a growing need for effective methods of removing chloride and potassium from the chemical cycles employed in the cellulose industry.